Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758354AbcCVNAg (ORCPT ); Tue, 22 Mar 2016 09:00:36 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:46224 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758694AbcCVNA1 (ORCPT ); Tue, 22 Mar 2016 09:00:27 -0400 Subject: Re: [PATCH] spi: rockchip: fix warning of static check To: Shawn Lin , Mark Brown References: <1458646574-12830-1-git-send-email-shawn.lin@rock-chips.com> <56F140E4.8010906@mentor.com> CC: , , Doug Anderson , Dan Carpenter From: Vladimir Zapolskiy Message-ID: <56F141E7.5030303@mentor.com> Date: Tue, 22 Mar 2016 15:00:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Icedove/38.1.0 MIME-Version: 1.0 In-Reply-To: <56F140E4.8010906@mentor.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [137.202.0.76] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2342 Lines: 71 On 22.03.2016 14:56, Vladimir Zapolskiy wrote: > Hi Shawn, > > On 22.03.2016 13:36, Shawn Lin wrote: >> Let's improve the check with -EPROBE_DEFER, otherwise >> we may pass on null pointer to PTR_ERR. That causes the >> static checker warning: passing zero to 'PTR_ERR'. >> >> Reported-by: Dan Carpenter >> Cc: Doug Anderson >> Cc: Dan Carpenter >> Signed-off-by: Shawn Lin >> --- >> >> drivers/spi/spi-rockchip.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c >> index bfeb0d4..2cb36d9 100644 >> --- a/drivers/spi/spi-rockchip.c >> +++ b/drivers/spi/spi-rockchip.c >> @@ -726,20 +726,24 @@ static int rockchip_spi_probe(struct platform_device *pdev) >> rs->dma_tx.ch = dma_request_slave_channel(rs->dev, "tx"); >> if (IS_ERR_OR_NULL(rs->dma_tx.ch)) { >> /* Check tx to see if we need defer probing driver */ >> - if (PTR_ERR(rs->dma_tx.ch) == -EPROBE_DEFER) { >> + if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) { > > won't it be easier to change dma_request_slave_channel() to > dma_request_chan() or dma_request_slave_channel_reason() and replace strange > IS_ERR_OR_NULL() check with IS_ERR() one? > > AFAIU that's almost what has been suggested by Doug and it is a better > fix than this one published. > > At the moment check for IS_ERR_OR_NULL() is too aggressive and quite > confusing, because dma_request_slave_channel() never returns NULL. Sorry for a typo, never returns IS_ERR() of course. >> ret = -EPROBE_DEFER; >> goto err_get_fifo_len; >> } >> dev_warn(rs->dev, "Failed to request TX DMA channel\n"); >> + rs->dma_tx.ch = NULL; >> } >> >> rs->dma_rx.ch = dma_request_slave_channel(rs->dev, "rx"); >> - if (!rs->dma_rx.ch) { >> - if (rs->dma_tx.ch) { >> + if (IS_ERR_OR_NULL(rs->dma_rx.ch)) { >> + if (rs->dma_tx.ch == ERR_PTR(-EPROBE_DEFER)) { > > Same as above. > >> dma_release_channel(rs->dma_tx.ch); >> rs->dma_tx.ch = NULL; >> + ret = -EPROBE_DEFER; >> + goto err_get_fifo_len; >> } >> dev_warn(rs->dev, "Failed to request RX DMA channel\n"); >> + rs->dma_rx.ch = NULL; >> } >> >> if (rs->dma_tx.ch && rs->dma_rx.ch) { >> > -- With best wishes, Vladimir